U.S. patent application number 16/206788 was filed with the patent office on 2019-04-18 for method for manufacturing semiconductor device.
This patent application is currently assigned to TAIWAN SEMICONDUCTOR MANUFACTURING CO., LTD.. The applicant listed for this patent is TAIWAN SEMICONDUCTOR MANUFACTURING CO., LTD.. Invention is credited to Shiu-Ko JANGJIAN, Chun-Che LIN, Jia-Ming LIN.
Application Number | 20190115220 16/206788 |
Document ID | / |
Family ID | 57536926 |
Filed Date | 2019-04-18 |
United States Patent
Application |
20190115220 |
Kind Code |
A1 |
LIN; Jia-Ming ; et
al. |
April 18, 2019 |
METHOD FOR MANUFACTURING SEMICONDUCTOR DEVICE
Abstract
A method includes etching a dummy gate to form an opening. A
gate dielectric layer is deposited in the opening. A blocking layer
is deposited over the gate dielectric layer, wherein the blocking
layer has a bottom portion over a bottom of the opening and a
sidewall portion over a sidewall of the opening. An adhesive layer
is deposited over the bottom portion of the blocking layer. A metal
layer is deposited over the adhesive layer, wherein the metal layer
is in contact with the sidewall portion of the blocking layer.
Inventors: |
LIN; Jia-Ming; (Tainan City,
TW) ; JANGJIAN; Shiu-Ko; (Tainan City, TW) ;
LIN; Chun-Che; (Tainan City, TW) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
TAIWAN SEMICONDUCTOR MANUFACTURING CO., LTD. |
Hsinchu |
|
TW |
|
|
Assignee: |
TAIWAN SEMICONDUCTOR MANUFACTURING
CO., LTD.
Hsinchu
TW
|
Family ID: |
57536926 |
Appl. No.: |
16/206788 |
Filed: |
November 30, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14754427 |
Jun 29, 2015 |
|
|
|
16206788 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H01L 29/517 20130101;
H01L 29/66545 20130101; H01L 21/76843 20130101; H01L 21/76879
20130101; H01L 29/513 20130101; H01L 21/28568 20130101; H01L
21/28088 20130101; H01L 29/4966 20130101 |
International
Class: |
H01L 21/285 20060101
H01L021/285; H01L 21/28 20060101 H01L021/28; H01L 21/768 20060101
H01L021/768; H01L 29/66 20060101 H01L029/66; H01L 29/49 20060101
H01L029/49 |
Claims
1. A method, comprising: etching a dummy gate to form an opening;
depositing a gate dielectric layer in the opening; depositing a
blocking layer over the gate dielectric layer, wherein the blocking
layer has a bottom portion over a bottom of the opening and a
sidewall portion over a sidewall of the opening; depositing an
adhesive layer over the bottom portion of the blocking layer; and
depositing a metal layer over the adhesive layer, wherein the metal
layer is in contact with the sidewall portion of the blocking
layer.
2. The method of claim 1, wherein the metal layer is in contact
with the adhesive layer.
3. The method of claim 1, wherein depositing the metal layer is
performed such that the opening is filled with the metal layer in a
substantially bottom-up manner.
4. The method of claim 1, wherein the adhesive layer comprises
boron.
5. The method of claim 1, wherein the adhesive layer comprises
silicon.
6. The method of claim 1, wherein depositing the adhesive layer is
performed such that the sidewall portion of the blocking layer is
at least partially free from coverage by the adhesive layer.
7. The method of claim 1, wherein depositing the adhesive layer is
performed using physical vapor deposition (PVD).
8. The method of claim 1, wherein the metal layer comprises
tungsten.
9. A method, comprising: etching a dummy gate to form an opening;
depositing a gate dielectric layer in the opening; depositing,
using an anisotropic deposition process, an adhesive layer over the
gate dielectric layer, wherein the anisotropic deposition process
has a first deposition rate over a bottom of the opening and a
second deposition rate over a sidewall of the opening, and the
first deposition rate is higher than the second deposition rate;
and depositing a metal layer over the adhesive layer.
10. The method of claim 9, wherein the anisotropic deposition
process comprises collimated physical vapor deposition (PVD), radio
frequency physical vapor deposition (RFPVD), or combinations
thereof.
11. The method of claim 9, wherein depositing the adhesive layer is
performed such that a least a portion of the sidewall of the
opening is free from coverage by the adhesive layer.
12. The method of claim 9, wherein depositing the metal layer is
performed such that the metal layer tends to be deposited over the
bottom of the opening rather than over the sidewall of the
opening.
13. The method of claim 9, further comprising: removing an excess
portion of the metal layer external to the opening.
14. A method, comprising: etching a dummy gate to form an opening;
depositing a gate dielectric layer in the opening; depositing a
first blocking layer over the gate dielectric layer, wherein the
first blocking layer has a bottom portion over a bottom of the
opening and a sidewall portion over a sidewall of the opening;
depositing an adhesive layer over the bottom portion of the first
blocking layer, wherein the sidewall portion of the first blocking
layer is at least partially free from coverage by the adhesive
layer; and depositing a metal layer over the adhesive layer.
15. The method of claim 14, wherein depositing the metal layer is
performed such that a sidewall of the metal layer is in contact
with the sidewall portion of the first blocking layer.
16. The method of claim 14, wherein depositing the metal layer is
performed such that a bottom surface of the metal layer is in
contact with the bottom portion of the adhesive layer.
17. The method of claim 14, wherein the first blocking layer
comprises titanium nitride, tantalum nitride, or combinations
thereof.
18. The method of claim 14, further comprising: depositing a work
function metal layer over the gate dielectric layer prior to
depositing the first blocking layer.
19. The method of claim 18, further comprising: depositing a second
blocking layer over the gate dielectric layer prior to depositing
the work function metal layer.
20. The method of claim 14, wherein the adhesive layer comprises
tungsten.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] The present application is a Divisional Application of the
U.S. application Ser. No. 14/754,427, filed Jun. 29, 2015, which is
herein incorporated by reference.
BACKGROUND
[0002] The continuous effort to improve semiconductor device
performance brings with it a continuous effort of scaling down
device feature sizes thereby improving the device performance speed
and its functional capability. In the course of semiconductor
integrated circuit (IC) evolution, functional density (i.e., the
number of interconnected devices per chip area) has generally
increased while geometry size (i.e., the smallest component (or
line) that can be created using a fabrication process) has
decreased. Such scaling down has also increased the complexity of
IC processing and manufacturing.
BRIEF DESCRIPTION OF THE DRAWINGS
[0003] Aspects of the present disclosure are best understood from
the following detailed description when read with the accompanying
figures. It is noted that, in accordance with the standard practice
in the industry, various features are not drawn to scale. In fact,
the dimensions of the various features may be arbitrarily increased
or reduced for clarity of discussion.
[0004] FIGS. 1A to 1G are cross-sectional views of a method for
manufacturing a semiconductor device at various stages in
accordance with some embodiments of the present disclosure.
[0005] FIGS. 2A to 2D are cross-sectional views of a method for
manufacturing a semiconductor device at various stages in
accordance with some embodiments of the present disclosure.
DETAILED DESCRIPTION
[0006] The following disclosure provides many different
embodiments, or examples, for implementing different features of
the provided subject matter. Specific examples of components and
arrangements are described below to simplify the present
disclosure. These are, of course, merely examples and are not
intended to be limiting. For example, the formation of a first
feature over or on a second feature in the description that follows
may include embodiments in which the first and second features are
formed in direct contact, and may also include embodiments in which
additional features may be formed between the first and second
features, such that the first and second features may not be in
direct contact. In addition, the present disclosure may repeat
reference numerals and/or letters in the various examples. This
repetition is for the purpose of simplicity and clarity and does
not in itself dictate a relationship between the various
embodiments and/or configurations discussed.
[0007] Further, spatially relative terms, such as "beneath,"
"below," "lower," "above," "upper" and the like, may be used herein
for ease of description to describe one element or feature's
relationship to another element(s) or feature(s) as illustrated in
the figures. The spatially relative terms are intended to encompass
different orientations of the device in use or operation in
addition to the orientation depicted in the figures. The apparatus
may be otherwise oriented (rotated 90 degrees or at other
orientations) and the spatially relative descriptors used herein
may likewise be interpreted accordingly.
[0008] FIGS. 1A to 1G are cross-sectional views of a method for
manufacturing a semiconductor device at various stages in
accordance with some embodiments of the present disclosure.
Reference is made to FIG. 1A. A substrate 110 is provided. The
substrate 110 may be a semiconductor substrate, including silicon,
germanium, silicon germanium, gallium arsenide (GaAs) or other
appropriate semiconductor materials. Alternatively, the substrate
110 may include an epitaxial layer (not shown). Furthermore, the
substrate 110 may be strained for performance enhancement.
Alternatively, the substrate 110 may include a
semiconductor-on-insulator (SOI) structure such as a buried
dielectric layer. Also alternatively, the substrate 110 may include
a buried dielectric layer such as a buried oxide (BOX) layer, such
as that formed by a method referred to as separation by
implantation of oxygen (SIMOX) technology, wafer bonding, selective
epitaxial growth (SEG), or other appropriate methods. The substrate
110 may also include a fin structure of a fin-like field-effect
transistor (FinFET) formed by suitable processes, such as
lithography patterning process and etching process. In fact various
embodiments may include any of a variety of substrate structures
and materials.
[0009] The substrate 110 also includes various doped regions (not
shown) formed by implantation techniques. For example, a portion of
the substrate 110 is doped to form a P-type region and a P-well
where an n-channel device will be fabricated. Similarly, another
portion of the substrate 110 can be doped to form an N-type region
and an N-well where a p-channel device will be fabricated. The
doped regions are doped with P-type dopants, such as boron or
BF.sub.2, and/or N-type dopants, such as phosphorus or arsenic. The
doped regions may be formed directly on the substrate 110, in a
P-well structure, in an N-well structure, in a dual-well structure,
or using a raised structure.
[0010] The substrate 110 also includes various isolation features,
such as shallow trench isolation (STI) (not shown), formed in the
substrate 110 to separate various devices. The formation of the STI
may include etching a trench in the substrate 110, filling the
trench by dielectric materials such as silicon oxide, silicon
nitride, or silicon oxynitride and using chemical mechanical
polishing (CMP) to remove the excessive dielectric metals
layers.
[0011] In FIG. 1A, a dielectric material 120' is formed on the
substrate 110 by any appropriate method, such as atomic layer
deposition (ALD), chemical vapor deposition (CVD) and ozone
oxidation. ALD is a gas phase chemical process and it is a
self-limiting atomic layer-by-layer growth method. The
surface-controlled growth mechanism of ALD provides good step
coverage and dense films with few (or no) pinholes. The precision
achieved with ALD allows processing of extremely thin films in a
controlled way in the nanometer scale. The dielectric material 120'
includes oxide, HfSiO and/or oxynitride. It has been observed that
the dielectric material 120' may provide a remedy for some
high-.kappa. dielectric gate stack integration issues, such as
threshold voltage pinning and reducing carrier mobility. The
dielectric material 120' may also be a diffusion blocking to
prevent undesirable interface reactions between the high-.kappa.
dielectric material and the substrate 110.
[0012] A gate material 210', such as polysilicon, is disposed on or
above the dielectric material 120' by deposition techniques known
in the art. Alternatively, an amorphous silicon layer may
optionally be formed instead of the polysilicon layer. Additionally
a patterned hard mask 300 is formed on the gate material 210'. The
patterned hard mask 300 includes silicon nitride and/or silicon
oxide, or alternatively photoresist. The patterned hard mask 300
may include multiple layers. The patterned hard mask 300 is
patterned by a photolithography process and an etching process.
[0013] Reference is made to FIG. 1B. By using the patterned hard
mask 300 of FIG. 1A as an etch mask, an etching process is applied
to form a dummy gate stack 200. The dummy gate stack 200 includes a
dummy gate 210 patterned from the gate material 210' (see FIG. 1A)
and an interfacial layer (IL) 120 patterned from the dielectric
material 120' (see FIG. 1A). The etching process includes a dry
etch, a wet etch, or a combination of dry etch and wet etch. The
dry etching process may implement fluorine-containing gas (e.g.,
CF.sub.4, SF.sub.6, CH.sub.2F.sub.2, CHF.sub.3, and/or
C.sub.2F.sub.6), chlorine-containing gas (e.g., Cl.sub.2,
CHCl.sub.3, CCl.sub.4, and/or BCl.sub.3), bromine-containing gas
(e.g., HBr and/or CHBr.sub.3), iodine-containing gas, other
suitable gases and/or plasmas, and/or combinations thereof. The
etching process may include a multiple-step etching to gain etch
selectivity, flexibility and desired etch profile.
[0014] After the dummy gate stack 200 is formed, sidewall spacers
130 are formed on the sidewalls of the dummy gate stack 200. The
sidewall spacers 130 may include a dielectric material such as
silicon oxide, silicon nitride, silicon carbide, silicon
oxynitride, or combinations thereof. In some embodiments, the two
sidewall spacers 130 are respectively formed by multiple layers or
multiple spacers. For example, a seal spacer is formed on the
sidewall of the dummy gate stack 200 first, then a main spacer is
formed on the seal spacer. The sidewall spacers 130 may be formed
by deposition and etch processes known in the art.
[0015] Reference is made to FIG. 1C. The dummy gate 210 of FIG. 1B
is removed to form an opening 105. In some embodiments, before
removing the dummy gate 210, a dielectric layer 140 is formed at
outer sides of the sidewall spacers 130 on the substrate 110. The
dielectric layer 140 includes silicon oxide, oxynitride or other
suitable materials. The dielectric layer 140 includes a single
layer or multiple layers. The dielectric layer 140 is formed by a
suitable technique, such as CVD or ALD. A chemical mechanical
planarization (CMP) process may be applied to remove excessive
dielectric layer 140 and expose the top surface of the dummy gate
210 to a subsequent dummy gate removing process.
[0016] In the present disclosure, a replacement gate (RPG) process
scheme is employed. Generally, in a RPG process scheme, a dummy
polysilicon gate is formed first and is replaced later by a metal
gate after high thermal budget processes are performed. In some
embodiments, the dummy gate 210 (see FIG. 1B) is removed to form
the opening 105 with the sidewall spacer 130 as its sidewall. In
some other embodiments, the interfacial layer 120 is removed as
well. Alternatively, in some embodiments, the dummy gate 210 is
removed while the interfacial layer 120 retains. The dummy gate 210
(and the interfacial layer 120) may be removed by dry etch, wet
etch, or a combination of dry and wet etch. For example, a wet etch
process may include exposure to a hydroxide containing solution
(e.g., ammonium hydroxide), deionized water, and/or other suitable
etchant solutions.
[0017] Reference is made to FIG. 1D. A high-.kappa. dielectric
layer 150' is conformally formed in the opening 105. In some
embodiments, another interfacial layer is deposited first if the
interfacial layer 120 of FIG. 1B is removed in a previous process
step. The high-.kappa. dielectric layer 150' may include LaO, AlO,
ZrO, TiO, Ta.sub.2O.sub.5, Y.sub.2O.sub.3, SrTiO.sub.3 (STO),
BaTiO.sub.3 (BTO), BaZrO, HfZrO, HfLaO, HfSiO, LaSiO, AlSiO, HfTaO,
HfTiO, (Ba,Sr)TiO.sub.3 (BST), Al.sub.2O.sub.3, Si.sub.3N.sub.4,
oxynitrides (SiON), or other suitable materials. The high-.kappa.
dielectric layer 150' is deposited by suitable techniques, such as
ALD, CVD, physical vapor deposition (PVD), thermal oxidation,
combinations thereof, or other suitable techniques. PVD is a
deposition method which involves physical processes such as a
plasma sputter bombardment rather than involving a chemical
reaction at the surface. In the plasma sputter process, atoms or
molecules are ejected from a target material by high-energy
particle bombardment so that the ejected atoms or molecules can
condense on a substrate as a thin film.
[0018] Subsequently, a cap layer 155' is conformally formed on the
high-.kappa. dielectric layer 150'. The cap layer 155' is
configured to conduct electricity and prevent inter-diffusion and
reaction between high-.kappa. dielectric layer 150' and a metal
gate layer. The cap layer 155' may include refractory metals and
their nitrides (e.g. TiN, TaN, W.sub.2N, TiSiN, TaSiN). The cap
layer 155' may be deposited by PVD, CVD, Metal-organic chemical
vapor deposition (MOCVD) and ALD.
[0019] Then, a blocking layer 160' is conformally formed on the cap
layer 155'. The blocking layer 160' may include metal nitride
materials. For example, the blocking layer 160' includes TiN, TaN,
or combination thereof. In some embodiments, the blocking layer
160' includes a single layer or multiple layers. For a
multiple-layer configuration, the layers include different
compositions of metal nitride from each other. For example, the
blocking layer 160' has a first metal nitride layer including TiN
and a second metal nitride layer including TaN. The blocking layer
160' is configured to inhibit diffusion of metal ions from a metal
layer (i.e., a work function metal layer 165' herein) to adjacent
layers, thereby inhibiting the formation of the undesirable voids
in the vicinity of the work function metal layer 150' of the gate
stack 200.
[0020] Subsequently, a work function metal layer 165' is
conformally formed on the blocking layer 160'. In some embodiments,
the work function metal layer 165' may include a single layer or
multi layers, such as a work function film, a liner film, a wetting
film, and an adhesion film. The work function metal layer 165' may
include Ti, TiAl, TiAlN, TaC, TaCN, TaSiN, Mn, Zr, TiN, TaN, Ru,
Mo, WN, Co, Al, or any suitable materials. For example, the work
function metal layer 165' includes at least one of Ti, Al, or TiAl
when a metal gate stack 250 (see FIG. 1G) is part of an N-channel
MOS (NMOS) transistor of a complementary MOS (CMOS) device.
Alternatively, the work function metal layer 165' includes at least
one of TiN, Co, WN, or TaC when the metal gate stack 250 (see FIG.
1G) is part of a P-channel MOS (PMOS) transistor of the CMOS
device. The work function metal layer 165' may be formed by ALD,
PVD, CVD, or other suitable process.
[0021] Then, a blocking layer 170' is conformally formed on the
work function metal layer 165'. The blocking layer 170' may include
metal nitride materials. For example, the blocking layer 170'
includes TiN, TaN, or combination thereof. In some embodiments, the
blocking layer 170' includes a single layer or multiple layers. For
a multiple-layer configuration, the layers include different
compositions of metal nitride from each other. For example, the
blocking layer 170' has a first metal nitride layer including TiN
and a second metal nitride layer including TaN. The blocking layer
170' is configured to inhibit diffusion of metal ions from a metal
layer (i.e., a gate electrode 190 in FIG. 1G) to adjacent layers,
thereby inhibiting the formation of the undesirable voids in the
vicinity of the gate electrode 190 of the metal gate stack 250.
After the formation of the blocking layer 170', the size of the
opening 105 is reduced to the opening 175. The opening 175 has a
bottom surface 175b and two sidewalls 175s.
[0022] Reference is made to FIG. 1E. A metal adhesive 180 is
anisotropically formed on the blocking layer 170' and in the
opening 175, such that the metal adhesive 180 is disposed on the
bottom surface 175b of the opening 175 while leaving at least a
portion of the sidewall 175s of the opening 175 exposed. The
anisotropic deposition method employed to deposit the metal
adhesive 180 can be any method that provides a directional
deposition so that more metal adhesive material is deposited on
horizontal surfaces than on vertical surfaces. For example, the
anisotropic deposition method can be a collimated physical vapor
deposition (PVD) method, in which the first metallic material is
directed downward in directions substantially parallel to the
vertical direction of the exemplary semiconductor structure.
Alternately, the anisotropic deposition method can employ radio
frequency physical vapor deposition (RFPVD) sputtering and/or with
constant voltage substrate bias, i.e., constant electrical voltage
bias applied to the substrate. The deposition rate depends on the
angle of incidence of incoming particles, resulting in a higher
deposition rate on the bottom surface 175b than the sidewalls 175s
of the opening 175. In some embodiments, the metal adhesive 180 is
made of metal alloy. In some other embodiments, the metal adhesive
180 is made of silicon (Si), boron (B), tungsten silicon
(WSi.sub.x), tungsten boron (WB.sub.x), tungsten boron silicon
(WSi.sub.xB), or any combination thereof.
[0023] Since the metal adhesive 180 is formed by using the
anisotropically deposition process, the metal adhesive 180 is
deposited on the bottom surface 175b of the opening 175 and
substantially exposes the sidewalls 175s of the opening 175. In
some embodiments, a thickness T of the metal adhesive 180 is about
1 angstrom to about 20 angstrom.
[0024] Reference is made to FIG. 1F. The remaining opening 175 is
filled with a metal layer 190' on the metal adhesive 180. In some
embodiments, the metal layer 190' includes tungsten (W). The metal
layer 190' is deposited by ALD, PVD, CVD, or other suitable
process. Since tungsten has a good adherence to silicon, boron,
tungsten silicon, tungsten boron, tungsten boron silicon, or
combination thereof, the tungsten can easily adhere to the metal
adhesive 180. Therefore, the remaining opening 175 is filled in a
bottom-up manner, without leaving a void, which may degrade device
yield and cause reliability problems, such as delamination and
electromigration during reliability testing. In some other
embodiments, the metal layer 190' includes aluminum (Al), copper
(Cu) or other suitable conductive material.
[0025] Reference is made to FIG. 1G. In some embodiments, a CMP
process is applied to remove excessive the metal layer 190' (see
FIG. 1F) to provide a substantially planar top surface for the
metal layer 190', the blocking layers 170' and 160', the work
function metal layer 165', the cap layer 155', and the high-.kappa.
dielectric layer 150' (see FIG. 1F). The remaining metal layer 190'
is a gate electrode 190, the remaining blocking layers 170' and
160' are respectively blocking layers 170 and 160, the remaining
work function metal layer 165' is a work function metal layer 165,
the remaining cap layer 155' is a cap layer 155, and the remaining
high-.kappa. dielectric layer 150' is a high-.kappa. dielectric
layer 150. The gate electrode 190, the metal adhesive 180, the
blocking layers 170 and 160, the work function metal layer 165, the
cap layer 155, and the high-.kappa. dielectric layer 150 together
form the metal gate stack 250.
[0026] In FIGS. 1A-1G, before the metal layer 190' is formed, the
metal adhesion 180 is formed above the bottom surface 175b of the
opening 175, i.e., at the bottom of the opening 175 when the
blocking layer 170 is formed. Since the metal adhesion layer 180 is
anisotropically formed in the opening 175, the metal adhesion layer
180 is formed at the bottom of the opening 175. The metal adhesive
180 can adhere metal materials of the metal layer 190'. Hence, the
metal layer 190' can be formed in a bottom-up manner. The metal
adhesive 180 enables the metal layer 190' to have improved filling
characteristics in the remaining opening 175, and therefore results
in a continuous void-free metal gate stack 250 by facilitating
filling of the remaining opening 175 with the metal such as
tungsten thereof for forming the gate electrode 190 without leaving
unfilled voids therein. The voids generated in a gate electrode may
deteriorate an electrical characteristic and reliability of the
gate electrode, increase the resistance of the gate electrode,
and/or weaken the structural integrity of the gate electrode.
Therefore, the configuration of FIG. 1G can improve the
abovementioned problems. The metal adhesive 180 can be made of
silicon (Si), boron (B), tungsten silicon (WSi.sub.x), tungsten
boron (WB.sub.x), tungsten boron silicon (WSi.sub.xB), or any
combination thereof. In some embodiments, the thickness T of the
metal adhesive 180 is about 1 angstrom to about 20 angstrom.
[0027] The formation of void-free metal material in an opening can
be applied to form a metal plug in a semiconductor device. FIGS. 2A
to 2D are cross-sectional views of a method for manufacturing a
semiconductor device at various stages in accordance with some
embodiments of the present disclosure. Reference is made to FIG.
2A. A substrate 110 is provided. The substrate 110 may be a
semiconductor substrate, including silicon, germanium, silicon
germanium, gallium arsenide or other appropriate semiconductor
materials. Alternatively, the substrate 110 may include an
epitaxial layer (not shown). Furthermore, the substrate 110 may be
strained for performance enhancement. Alternatively, the substrate
110 may include a semiconductor-on-insulator (SOI) structure such
as a buried dielectric layer. Also alternatively, the substrate 110
may include a buried dielectric layer such as a buried oxide (BOX)
layer, such as that formed by a method referred to as separation by
implantation of oxygen (SIMOX) technology, wafer bonding, selective
epitaxial growth (SEG), or other appropriate methods. The substrate
110 may also include a fin structure of a fin-like field-effect
transistor (FinFET) formed by suitable processes, such as
lithography patterning process and etching process. In fact various
embodiments may include any of a variety of substrate structures
and materials.
[0028] The substrate 110 also includes various doped regions formed
by implantation techniques. For example, in FIG. 2A, a portion of
the substrate 110 is doped to form a doped region 112. The doped
region 112 can be a P-type region or an N-type region. In some
embodiments, the doped region 112 can be doped with P-type dopants,
such as boron or BF.sub.2, and/or N-type dopants, such as
phosphorus or arsenic. The doped region 112 may be formed directly
on the substrate 110, in a P-well structure, in an N-well
structure, in a dual-well structure, or using a raised
structure.
[0029] The substrate 110 also includes various isolation features,
such as shallow trench isolation (STI) (not shown), formed in the
substrate 110 to separate various devices. The formation of the STI
may include etching a trench in the substrate 110, filling the
trench by dielectric materials such as silicon oxide, silicon
nitride, or silicon oxynitride and using chemical mechanical
polishing (CMP) to remove the excessive dielectric metals
layers.
[0030] In FIG. 2A, a dielectric layer 410 is formed on the
substrate 110. The dielectric layer 410 includes silicon oxide,
oxynitride or other suitable materials. The dielectric layer 410
includes a single layer or multiple layers. The dielectric layer
410 is formed by a suitable technique, such as CVD or ALD.
[0031] Reference is made to FIG. 2B. An opening 415 (or a via) is
formed in the dielectric layer 410 to expose the doped region 112
of the substrate 110. In some embodiments, the opening 415 can be
formed via use of standard photolithographic and RIE procedures,
using CHF.sub.3 as an etchant. In some other embodiments,
appropriate etchants and techniques to provide high
etch-rate-ratios are well known to those practicing this art. In
FIG. 2B, the opening 415 has a bottom surface 415b and a sidewall
415s. In FIG. 2B, the bottom surface 415b is a top surface of the
doped region 112 exposed by the opening 415.
[0032] Reference is made to FIG. 2C. A metal adhesive 180 is
anisotropically formed in the opening 415 and on the bottom surface
415b. The anisotropic deposition method employed to deposit the
metal adhesive 180 can be any method that provides a directional
deposition so that more metal adhesive material is deposited on
horizontal surfaces than on vertical surfaces. For example, the
anisotropic deposition method can be a collimated physical vapor
deposition (PVD) method, in which the first metallic material is
directed downward in directions substantially parallel to the
vertical direction of the exemplary semiconductor structure.
Alternately, the anisotropic deposition method can employ radio
frequency physical vapor deposition (RFPVD) sputtering and/or with
constant voltage substrate bias, i.e., constant electrical voltage
bias applied to the substrate. The deposition rate depends on the
angle of incidence of incoming particles, resulting in a higher
deposition rate on the bottom surface 415b than the sidewall 415s
of the opening 415. In some embodiments, the metal adhesive 180 is
made of metal alloy. In some other embodiments, the metal adhesive
180 is made of silicon (Si), boron (B), tungsten silicon
(WSi.sub.x), tungsten boron (WB.sub.x), tungsten boron silicon
(WSi.sub.xB), or any combination thereof.
[0033] Since the metal adhesive 180 is formed by using the
anisotropically deposition process, the metal adhesive 180 is
deposited on the bottom surface 415b of the opening 415 and
substantially exposes the sidewall 415s of the opening 415. In some
embodiments, a thickness T of the metal adhesive 180 is about 1
angstrom to about 20 angstrom.
[0034] Reference is made to FIG. 2D. A metal plug 420 is formed in
the remaining opening 415 and on the metal adhesive 180. In some
embodiments, the metal plug 420 includes tungsten (W). For example,
a metal layer is deposited to fill the opening 415 by ALD, PVD,
CVD, or other suitable process. Then, the metal layer is patterned
with photoresist and etched back to define the metal plug 420.
Since tungsten has a good adherence to silicon, boron, tungsten
silicon, tungsten boron, tungsten boron silicon, or combination
thereof, the tungsten can easily adhere to the metal adhesive 180.
Therefore, the remaining opening 415 is filled in a bottom-up
manner, without leaving a void, which may degrade device yield and
cause reliability problems, such as delamination and
electromigration during reliability testing. In some other
embodiments, the metal plug 420 includes aluminum (Al), copper (Cu)
or other suitable conductive material.
[0035] In FIGS. 2A-2D, before the metal plug 420 is formed, the
metal adhesive 180 is formed on the bottom surface 415b of the
opening 415. Since the metal adhesive 180 is anisotropically formed
in the opening 415, the metal adhesive 180 is formed at the bottom
of the opening 415. The metal adhesive 180 can adhere metal
materials of the metal plug 420. Hence, the metal plug 420 can be
formed in a bottom-up manner. The metal adhesive 180 enables the
metal plug 420 to have improved filling characteristics in the
remaining opening 415, and therefore results in a continuous
void-free metal plug 415 by facilitating filling of the remaining
opening 415 with the metal such as tungsten thereof for forming the
metal plug 420 without leaving unfilled voids therein. The metal
adhesive 180 can be made of silicon (Si), boron (B), tungsten
silicon (WSi.sub.x), tungsten boron (WB.sub.x), tungsten boron
silicon (WSi.sub.xB), or any combination thereof. In some
embodiments, the thickness T of the metal adhesive 180 is about 1
angstrom to about 20 angstrom. In some other embodiments, the metal
plug can be a plug formed in the interlayer dielectric (ILD).
[0036] According to some embodiments of the present disclosure, a
method for manufacturing a semiconductor device includes etching a
dummy gate to form an opening. A gate dielectric layer is deposited
in the opening. A blocking layer is deposited over the gate
dielectric layer, wherein the blocking layer has a bottom portion
over a bottom of the opening and a sidewall portion over a sidewall
of the opening. An adhesive layer is deposited over the bottom
portion of the blocking layer. A metal layer is deposited over the
adhesive layer, wherein the metal layer is in contact with the
sidewall portion of the blocking layer.
[0037] According to some embodiments of the present disclosure, a
method for manufacturing a semiconductor device includes etching a
dummy gate to form an opening. A gate dielectric layer is deposited
in the opening. An adhesive layer is deposited, using an
anisotropic deposition process, over the gate dielectric layer,
wherein the anisotropic deposition process has a first deposition
rate over a bottom of the opening and a second deposition rate over
a sidewall of the opening, and the first deposition rate is higher
than the second deposition rate. A metal layer is deposited over
the adhesive layer.
[0038] According to some embodiments of the present disclosure, a
method for manufacturing a semiconductor device includes etching a
dummy gate to form an opening. A gate dielectric layer is deposited
in the opening. A first blocking layer is deposited over the gate
dielectric layer, wherein the first blocking layer has a bottom
portion over a bottom of the opening and a sidewall portion over a
sidewall of the opening. An adhesive layer is deposited over the
bottom portion of the first blocking layer, wherein the sidewall
portion of the first blocking layer is at least partially free from
coverage by the adhesive layer. A metal layer is deposited over the
adhesive layer.
[0039] The foregoing outlines features of several embodiments so
that those skilled in the art may better understand the aspects of
the present disclosure. Those skilled in the art should appreciate
that they may readily use the present disclosure as a basis for
designing or modifying other processes and structures for carrying
out the same purposes and/or achieving the same advantages of the
embodiments introduced herein. Those skilled in the art should also
realize that such equivalent constructions do not depart from the
spirit and scope of the present disclosure, and that they may make
various changes, substitutions, and alterations herein without
departing from the spirit and scope of the present disclosure.
* * * * *